Bismuth‐Decorated Silicon Photocathodes for CO2‐to‐Formate Solar‐Driven Conversion.

The integration of metal‐based catalysts onto semiconducting electrodes provides a real benefit for the CO2 electrochemical conversion because it allows the electrochemical process to be activated by photogenerated electrons. In that context, we report here that silicon photocathodes modified with electrodeposited Bi nanostructures are highly active for the photoelectrocatalytic conversion of CO2 to formate. Through the consumed electrical charge and the electrodeposition time, it is possible to finely control both the structure and the density of the deposited catalyst. The optimal photocathode was prepared by using a 5 s electrodeposition time and exhibited the highest photocurrent density (−24.1 mA cm−2) with partial formate photocurrent density jformate=−17.4 mA cm−2 at −1.03 V vs Reversible Hydrogen Electrode (RHE), i. e. a 0.84 V overpotential for CO2 to formate conversion in CO2‐saturated 0.5 M KHCO3 solution. Such values highlight the excellent photoelectrocatalytic activity of our photocathodes. [ABSTRACT FROM AUTHOR]